class Stack:
    """栈基础类"""

    def __init__(self):
        pass

    def append(self, *args, **kwargs):
        """栈顶添加元素"""
        pass

    def pop(self, *args, **kwargs):
        """栈顶退出元素"""
        pass

    def is_empty(self, *args, **kwargs):
        """栈是否为空"""
        pass

    def top(self):
        """返回栈顶元素"""
        pass

    def get_stack(self):
        """获取栈结构"""
        pass

